Madlib has a consistently amazing album (Madvillain), something that Dilla never really managed to create (except perhaps for fantastic vol 1). Madlib also has a lot of great side projects (quasimoto, YNQ,), whereas Dilla never really had that. Madlib also has an album with longer song structures that involve many samples (Shades of blue), whereas Dilla never had that either.

I still love Dilla a lot but this really isn't as clear as people are making it seem.

I think Dilla is/was the more naturally gifted
a great deal of Madlib's talent has to do with the fact that he's a workalcoholic, has tons of dope records and a crazy ear for samples-worthy music
at 1st I thought Dilla was less adventurous/experimental than Madlib but the more I studied his discography and influences the more I realized it wasn't true
death cheated on him
can't imagine how further he could have went if he was still alive

On one hand Dilla has produced Iconic tracks with some of the dopest artists like Busta, Royce Da 5'9, Common, and many others even Madlib. On the Other hand Madlib is still here makin new shit and will still progress and experiment. I think we all see Dilla as a better producer and have tremendous respect for him because of the shit he's done and the fact that he's not here, and we all see Madlib as the better producer because of his variety to his music and the fact we can look forward to hearing new music from him cuz he's still here. This question is like knocking 2 small rocks together expecting them to break. Neither one really is the better producer cuz you can still get down to some Dilla and you can still get down to some Madlib, each of them has created tracks to fit your mood and vibe. I see no winner in my opinion it just depends on who you feel like listening to, either way they're both DOPE

Ooof. Dilla handled the drums and sirens well--technically gifted. Lib is my favorite based upon his taste--ability to dig--and the all-around (quiet) personality. I identify with dude too much to say differently.